build: add busybox for debugging

Author: echozio

Dockerfile

@@ -11,3 +11,9 @@ COPY --chown=0:0 --chmod=004 --from=alpine:latest /etc/ssl/certs/ca-certificates
 ENV SSL_CERT_FILE=/ca-certificates.crt
 COPY --chown=0:0 --chmod=001 --from=build /tmp/build/commit-status-poster /commit-status-poster
 ENTRYPOINT ["/commit-status-poster"]
+USER 0:0
+COPY --chown=0:0 --chmod=755 --from=busybox:musl /bin/busybox /busybox
+ENV PATH=/
+RUN ["/busybox", "--install", "/"]
+USER 1000:1000
+ENTRYPOINT ["/sleep", "infinity"]